why does my Volvo XC90's brake pedal feel spongy?

Solution

1. Preparation

• Tools Required: Brake fluid, brake bleeder kit, socket set, wrench set, vacuum gauge.
• Ensure the vehicle is parked on a level surface, and the engine is off.
• Allow the brakes to cool down if they have been used recently.

2. Check and Refill Brake Fluid

• Locate the master cylinder reservoir.
• Remove the cap and inspect the brake fluid level; add the appropriate brake fluid (DOT 4 for Volvo) if low.
• Check the fluid for contamination; if it appears dark or cloudy, it may need replacement.

3. Inspect Brake Lines and Components

• Visually inspect all brake lines for signs of wear, corrosion, or leaks.
• Check the calipers and wheel cylinders for fluid leaks.
• If leaks are found, replace the damaged components as needed.

4. Bleed the Brake System

• Attach a brake bleeder kit to the brake bleeder valve on each caliper.
• Start with the caliper farthest from the master cylinder (usually the right rear) and work towards the closest (left front).
• Open the bleeder valve and have an assistant press the brake pedal down.
• Close the valve before releasing the pedal. Repeat until no air bubbles are present in the fluid.
• Ensure to refill the master cylinder reservoir as fluid is bled out.

5. Test the Brake Booster

• Use a vacuum gauge to check the brake booster’s vacuum.
• With the engine running, disconnect the booster vacuum line and ensure there is vacuum present.
• If no vacuum is detected, inspect the vacuum source and replace the booster if necessary.